This thesis investigated the proposition by Johnson (1995; 1999) that there are distinct patterns of physical aggression within relationships, characterised as common couple violence and intimate terrorism. To investigate Johnson's theory, a stratified sample containing students (n=1 13), women from a domestic violence refuge (n=43), and male prisoners (n=108). Participants completed measures of physical aggression, escalation of physical aggression, controlling behaviour, fear of injuries, and actual injuries. Results of chapters 3 and 5 provided broad support for the view that there are distinct patterns of aggressive relationships corresponding to those identified by Johnson (1995; 1999). Chapter 4 found however, that the use of physical aggression was predicted by instrumental beliefs for both intimate terrorism and common couple violence, and analysis at the individual level (chapter 6) did not support the distinction between controlling and non-controlling partner aggression, but instead indicated that the use of physical aggression was associated with controlling behaviours in all relationship categories. To investigate Johnson's (1999) classification procedure in a non-stratified sample, a second sample was collected which consisted of 399 men and 951 women. In chapters 8 and 9 analysis was conducted separately for victim and perpetrator reports. Results were broadly supportive of Johnson's categories (though not the earlier findings regarding sex composition of the categories), but not the controlling noncontrolling dichotomy. Chapter 11 sought to investigate the ultimate aim of such behaviour and found that both men and women use more control when the woman was fecund, and more control and physical aggression when an individual had lower mate-value. The findings of this thesis are discussed in relation to sampling strategies, the control and physical aggression relationship and the effect of reporting2 bias. The conclusions from this thesis are that Johnson's dichotomy may not represent a qualitative difference, but instead may be one of quantity.